Well I wasn't really shopping for one (just got rid of my 73 twin) but it was too good of a deal to let pass by. I watched a vintage Vibrolux come down by $100 every few days on CL and picked it up for a song. Turns out its a 73.

It has a the sweetest vintage G10-60 Rola Celestrion's (sliver) in it which sound amazing - but they are 15 ohms each so its the wrong impedance for the amp. I'm looking for a 4 ohm load and getting a 7.5 ohm load.

I've got a 1x12 JBL ext cab with an 8 ohm E120. If I simply run this out of the ext speaker jack am I then giving my amp close to the correct load - assuming I also use the Rola's.

Good news is I already have a 2x12 JBL 4 ohm cab, but that's a bit much to lug around.

My trusted amp tech says I'll be fne at low living room volumes with the Rola's but will damage the transformers if I push them at a gig.

You scored James! I'd love to run into a good deal on that amp. My Twin ext speaker jack wants to see 4ohms also. It says so right on the amp. So your amp wants to see an 4 ohm load. You've got an 7.5 load from the Celestions wired in parallel. If you wired the 8 ohm JBL in parallel with the Celestions you will get a 4ohm load. An amp guru may have a better method?

The issue will be the 1 x 12 will be louder than the 2 15 ohm speakers (individually)....that's before sensitivity differences which will make it more pronounced (E120's are like the most sens ever...original cone/coil that is). Could be a good thing though. And yes Fender vintage spkr jacks are parallel so running 2 x 8 ohm loads (1 ext. and 1 reg jack) combine to show the trans. 4 ohms total.

Hey. Thanks guys! Looks like I'm good to go with two options. Disconnect the Rolas and use by 2x12 4 ohm d120 cab or simply plug in my 1x12 e120 cab and enjoy the jbl overtake those rola 's.

Back in grad school in the late 90s I wasn't playing a lot of electric, mostly accoustic. I got lazy moving so much and sold my SFDR I had bought new in 79. I've missed that amp but I have to say the Vibrolux is a better amp for my guitar collection and playing style.

I sold that DR for a song to a friend of a friend so I guess what comes around goes around.

I'm really enjoying it. I forgot how much fun it is to have a great amp at home and how plugging in solo gets the creative juices flowing.